The present invention relates to a method of transferring yarn packages in a textile machine such as a spinning frame or a winder having a plurality of spinning or winding stations arranged in a row on each longitudinal side of the machine.
In a spinning machine comprising a plurality of spinning units, each defining a spinning station of the machine, which are juxtaposed in a row on each side thereof and a single run of package transferring conveyor which is disposed to extend centrally along the spinning stations on each side from an end to the other end of the machine for transferring doffed full packages placed thereon, wherein a full package has a width, or an axial dimension thereof which is greater than half the interval distance at which the spinning units on each side are spaced from one another, there is a fear that a full package being doffed from a spinning station on one side of the machine onto the conveyor may interfere with a full package, if any, which has already been already doffed from another spinning station positioned just opposite the station on said one side and is thus still within the doffing area for both of the opposite stations on the conveyor. Thus, the full package previously doffed and placed for storage on the conveyor will provide an obstacle to the full package to be doffed from the opposite spinning station.
FIG. 1 shows a structure of a spinning frame proposed heretofore in an attempt to avoid the problem associated with the aforementioned interference between full packages, wherein the spinning frame 1 includes two lines of package transferring conveyors 3 each disposed along a yarn winding drum 2 extending on each longitudinal side of the machine 1. In operation, when a yarn coming out from a spinning unit (not shown) and then wound by the winding drum 2 is formed into a full package 4 of any desired size, it is pushed out of its winding position onto an adjacent conveyor 3 by any suitable means mounted on a doffing unit 5. The yarn packages 4 thus doffed from the respective spinning stations are temporaily stored on the conveyor 3 temporarily for any desired length of time, whereupon the conveyors 3 are started by a machine operator so that the packages 4 may be moved with the conveyors to be delivered from the machine 1.
In this proposed structure having one package transferring conveyor run for each row of spinning stations, however, the widthwise dimension of the machine 1 will naturally be larger than in the structure having only a single conveyor line of the thus posing a disadvantage in terms of the space factor and cost for machine installation. The complicated structure of the machine due to an added conveyor is also disadvantageous in terms of maintenance thereof. In addition, because connection of the conveyors with any package transferring system of a subsequent process can be accomplished only with greater difficulty, the additional conveyor makes it more difficult to provide such connection for the purpose of automation in yarn package handling in a spinning mill.
In order to solve the aforesaid problems, a method is proposed by U.S. patent application Ser. No. 506,296 for transferring full packages in a spinning frame having a plurality of spinning stations arranged in a row on each longitudinal side of a the frame, a single run of normally-stopped package transferring conveyor disposed centrally between the opposite rows of the stations and a doffing unit for providing doffing service at each of the stations while traveling around the machine, according to which method the doffing unit performs its doffing service at a spinning station only when no package is present on the conveyor at a doffing position corresponding to the station at which the doffing unit is then stopped, but it defers its doffing operation at said station if any package is present at said position on the conveyor. When the number of those full packages which are still undoffed and therefore reserved for later doffing amounts to a predetermined value, the conveyor is moved to discharge the doffed packages thereby to clear the conveyor.
This method of package transferring according to the above Application is disadvantageous in that the production efficiency of the machine may be affected depending upon the yarn number count, Ne, of the yarns to be spun on the machine. That is, in spinning finer count yarns which require a longer time for forming a full package of yarn at each of the spinning stations, the number of full packages which may be formed, and therefore which need be doffed on the machine in a given length of time is relatively few. Therefore, reservation of doffing at a spinning station due to the presence at its doffing position on the conveyor of any previously-doffed package takes place less frequently, which means less reduction in productive time of the spinning machine. Whereas, in producing packages from thicker count yarns calling for rather short times for forming full packages of the same size as in the above case, the number of packages to be completed on the machine in the same given length of time will naturally be increased. For example, in spinning yarns with a metric yarn number count Ne 6 at a spinning speed of 200 m/min for forming full packages with a diameter of 300 mm, it takes about three hours to complete a full package at each of the stations. On a spinning frame including as many as 192 working stations, a full package which needs be doffed will be formed approximately every minute. If the package forming time is thus reduced, as it would be now apparent to those skilled in the art, the reservation of doffing service takes place more frequently, thus increasing the dwell time when no yarn is spun out because no spinning operations are carried out at the spinning stations where doffing of their packages is reserved at least until the doffing unit comes again to such stations.
The result is, as a matter of course, that the production efficiency of the machine will be affected by the prolonged periods of time when no yarn is produced at any of the working stations, in particular when spinning thick count yarns.